Titanium aluminides are a class of alloys whose compositions include at least titanium and aluminum, and typically some additional alloying elements such as chromium, niobium, vanadium, tantalum, manganese, and/or boron. The gamma titanium aluminides are based on the gamma phase found at nearly the equiatomic composition, with roughly 50 atomic percent each of titanium and aluminum, or slightly reduced amounts to permit the use of other alloying elements. The titanium aluminides, and particularly the gamma titanium aluminides, have the advantages of low density, high stiffness, good low- and intermediate-temperature strength and cyclic deformation resistance, and good environmental resistance.
Gamma titanium aluminides can be used in aircraft engines. They potentially have applications such as exhaust nozzle flaps, diffusers, low pressure turbine brush seal supports, bearing supports, compressor casings, high pressure and low pressure hangars, frames, and low-pressure turbine blades and vanes. They may also have application in other products such as automotive valves and superchargers.
Articles made of gamma titanium aluminide alloys are usually cast from the melt into a mold, with investment casting being the most popular approach, and then further processed. If the article being fabricated is complexly shaped or too large in size to be cast as a single piece, it may be necessary to cast two or more pieces and then weld the pieces together. However, while operable procedures are available for performing surface welding of cast gamma titanium aluminide articles to repair casting surface defects, there is no technique available for joining two or more large, rigid, structural gamma titanium aluminide articles together by welding.
There exists a need for a method for joining pieces of gamma titanium aluminides together. The present invention fulfills this need, and further provides related advantages.